Examples of electron beam exposure apparatuses include an apparatus of the point-beam type which uses a beam in the shape of a spot, and an apparatus of the variable rectangular-beam type which uses a beam in the shape of a rectangular cross section whose size is variable.
The electron-beam exposure apparatus of the point-beam type draws using a single electron beam and is used exclusively for research and development purposes because of its low throughput. Though the electron-beam exposure apparatus of the variable rectangular-beam type has a throughput higher than that of the apparatus of the point-beam type by one to two orders, many problems still remain in terms of throughput in a case where a wafer is exposed to a pattern consisting of highly packed fine patterns on the order of 0.1 μm.
The stencil-mask type electron-beam exposure apparatus is an example of an apparatus that solves this problem. Specifically, this apparatus forms the desired pattern in a stencil mask as pattern through-holes and irradiates the stencil mask with an electron beam to thereby transfer the desired pattern to the sample surface via a demagnifying electron optics system. Another example of an apparatus that solves the above problem is a multi-electron beam exposure apparatus which irradiates a substrate having a plurality of apertures with an electron beam, irradiates the surface of a sample with a plurality of electron beams from the plurality of apertures, scans the plurality of electron beams across the sample surface by deflecting the electron beams, and turns the plurality of electron beams on and off individually in conformity with the pattern to be drawn, thereby drawing the pattern on the surface. A feature of both types of apparatus is that throughput can be improved by making the area exposed at one time, i.e., the area exposed, greater than that in the past.
However, with the stencil-mask type electron beam exposure apparatus, the pattern to be transferred will be distorted if the electron beam that irradiates the stencil mask exhibits non-uniform intensity in the irradiated area. With the multi-electron beam exposure apparatus, the pattern to be drawn will be distorted if the multiple electron beams exhibit a difference in intensity from one beam to the next. In particular, there will be a decline in the production yield of semiconductor integrated circuits if, during the exposure treatment, the electron-beam intensity distribution varies and becomes non-uniform or the multiple electron beams develop a difference in intensity.
In view of the problems set forth above, there is a need to implement highly reliable charged-particle-beam exposure by making it possible to control, in appropriate fashion, the intensity distribution of a charged-particle beam upon evaluating the uniformity of the charged-particle beam even during exposure.